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This search engine is so powerful that basically all the questions you want will be answered.
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This is relatively simple and easy to use.
Physics:
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Well-known foreign mathematical forums are more efficient than Baidu, and their answers are clearer, even citing references.
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All-encompassing, because the branches of chemistry are very different, so there are many terms in other foreign websites, which are more suitable.
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Finally, there is a domestic chemical engine, which is famous!
Also, recommend a technical article distribution center.
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Of course, the above information is useful, first of all, foreign languages should be excellent.